This invention relates to a vehicle suspension system and more particularly to a vehicle suspension system composed of elements consisting of a number of spring systems arranged in series to attenuate and damp vertical or horizontal shock waves.
Off the road vehicles, such as four wheel drive recreational vehicles, earth moving equipment and treaded vehicles such as tanks and tractors have in general compromised the ability of the vehicle's road suspension system to supply an isolation system over a wide range of road conditions by a requirement to protect the suspension system itself against damage from high intensity off the road shocks. The compromise in general has taken the form of limiting the travel of the suspension system by rubber bumpers that are contacted under high shock conditions by the vehicle's suspension system before the suspension system is damaged. Under unusually severe shock conditions, the rubber bumpers are not only contacted but compressed to the point where the rubber is no longer compressible and "hard bottoming" occurs. "Hard bottoming" results in the transmission of high shock loads to the vehicle's chassis and the vehicle's occupants.
Most vehicle suspension systems use helical, leaf or torsion bars to provide road shock isolation. Since only the leaf spring of these three types provides a small amount of damping, the vehicle's suspension must also include some type of damping device which may be hydraulic or a friction device. Since both of these damping devices are nonlinear, the suspension system becomes nonlinear and possibly subject to "hard bottoming" even if the limit of travel of the suspension system has not been reached.
Therefore, it is a primary object of this invention to provide a vehicle suspension element that will not only provide for the normal road isolation of a vehicle suspension system, but also for the abnormal condition of high shock load imposed by unusually rough terrain. It is also an object of this invention to provide a high degree of damping so that additional damping services, hydraulic or other types, are not required.
The patent to Blake, U.S. Pat. No. 3,770,232, discloses the combined use of an elastomeric annulus and sets of annular metal springs to absorb shocks received by a support member before they reach a platform on which a gas turbine or the like is mounted. The elastomeric annulus is connected directly to the shock-receiving support member so that the annulus immediately responds to such shocks. While this patent does disclose an elastomeric annulus and annular metal springs acting together to absorb shocks and vibration, it does not teach or suggest how these spring members could be applied to absorb shocks received by the two control arms of a vehicle.